The Sanitary/Pharmaceutical/Biotek industry's increasing use of process fabrications, the move toward block bodied and multiport diaphragm valve body designs, and the shrinking dimensional envelope for process components, has created a need for compact valve/pneumatic actuator packages. Low profile pneumatically actuated valve assemblies are used in these industries to provide such compact valve/actuator packages. Lower valve assembly heights are desirable in these applications because space is limited.
Present low profile pneumatically actuated valve assemblies typically have molded blind threaded inserts. Such inserts operate adequately when assembling the valve assembly to the valve body if the body's design provides full access to the assembly fasteners which are usually bolt fasteners. However, when the valve body requires a stud due to weldments prohibiting the use of a bolt fastener, actuators with blind inserts can not be assembled to the valve due to neither the stud nor the insert being able to rotate.
One solution to this problem has been to mount a cast stainless spool adapter between the valve body and actuator, in order to permit mounting to valve bodies requiring studs. This solution, however, undesirably added between 1.38" and 2.38" to the valve assembly's height.
Another solution to this problem has been to provide a cast bonnet made from stainless steel. The bonnet has lower and upper flanges. The lower flange permits the bonnet to be mounted to the valve body using studs in the valve body and nuts on the bonnet. The upper flange permits the lower actuator housing, which has blind threaded inserts molded in place, to be mounted to the bonnet by passing bolts through the bonnet's upper flange and threading them into the lower housing's blind inserts.
The cast bonnet design also has several limitations. The "bolt" pattern defined by the blind inserts in the lower actuator housing section, permit mounting of the bonnet in only one orientation relative to the valve body or process pipeline. The plastic lower housing section mounts in only one direction to the bonnet, hence, the housing's threaded air inlet boss position is not adjustable. This limits how close end users can run adjacent lines on the skid where space is limited due to interference of piping connections required to supply air to the lower housing section.
Another limitation of the cast bonnet/lower actuator housing design is that the bonnet and lower actuator housing section cannot be sealed from each other. If the process fluid is a chemical or solution that attacks the material of the plastic lower housing section, a failed valve diaphragm will result in contact of the process fluid and the lower housing material. The end result of this is a breakdown of the plastic material and eventually total failure of the component and risk of injury to the end user's operator.
Accordingly, a need exists for a low profile pneumatically actuated valve assembly which overcomes the shortcomings of the prior art.